Ask the Mechanic

By Steve Thompson, Contributing Editor

Q: My question is about starting my 7200 John Deere tractor in cold weather. The tractor has an auxiliary heater that plugs into a 110 outlet. It has a ground fault interrupter with a test button. My manual says to test before each use, but it doesn’t tell me how to test it. What should happen when I push the test button, and when do I use the reset button?

A: The block heater on your 7200 should begin to make the engine block feel “warm” in about 30 minutes. Also, if you have hearing better than mine, you can sometimes hear a slight “hissing” noise from the heating element. In extremely cold conditions, it could take up to two hours to warm the water.

The GFI on your tractor is hard to test. When the test button is pushed, if working properly, you will hear a “click,” the unit should go off, and the water will not heat at all. This test assures you the unit is working properly. With the reset button pushed, the button should stay in, and the water should heat. It is always recommended you check the unit by pushing the test button to make sure the unit is working.

Another way to check the unit is with a voltmeter. Check the volts before and after the GFI unit. The volts should be near 110 to 120. If you have volts after the GFI, but an amp meter shows no amp flow, then the heating element in the block is probably burned out. A note: The most common problem with the use of a GFI on a tractor block heater is using too small of a wire gauge on an extension cord to carry the amps needed for the heating element.

Q: I have a John Deere Model 40 “Popper.” The oil is getting out of the Touch-O-Matic hydraulic system into the engine. How can this be possible?

A: Hydraulic oil can get into the engine crankcase of the little ol’ 40 through the hydraulic pump. The hydraulic pump

on the 40 is mounted on the front of the engine and is driven by a gear on the engine.

In order to fix the problem, you will need to remove the pump (and probably the radiator). The kit (part number) that you need to repair your pump is AM1149T. You can probably do this repair yourself, but be careful not to lose any of the pieces inside—especially the little flat washer. It is special. A John Deere dealer could help you, as well.

I recommend changing the engine oil and filter after the repair is completed. Engine bearings and seals are not a big fan of hydraulic oil.

Q: I have a John Deere RX73 riding mower, recoil start, Kawasaki, 9 hp. It’s getting up in years but runs OK. After the last use, it suddenly “cut off,” indicating ignition loss. I removed the spark plug and placed it back on the spark plug cap, and attempted to arc it on the engine when pulling the cord. There was no arc, so I purchased a new spark plug and checked the mower safety switch, but I still had no arc.

So, I went to John Deere and purchased a new coil and plug cap that fits onto the end of the spark plug wire. I replaced the recoil mechanism and looked for spark. I still had no spark. I also tried a spark tester—still no spark.

The flywheel is tight on the crankshaft, the air gap between the coil and the flywheel is correct, and the magnet in the flywheel is clean and strong. The ignition seems so simple that I am at a loss. I give up and must “Ask the Mechanic.”

A: Let’s see if we can get your mower going again before you jerk the rope out of the mower. More than likely the problem with your mower is the little tin box that’s called a coil igniter. Nothing dies like a Deere with a bad igniter.

It is very rare that a coil gives any trouble on a Kawasaki, and since you replaced the coil, that pretty well rules out the coil.

However, the little igniter does cause trouble, and it is what tells the coil to fire. The igniter, mounted somewhere in the engine compartment, is an innocent-looking, small, shiny box about the size of a postage stamp, but it can stop a train and a lawn mower. The igniter should fix your problem.

I bet your old coil is OK. Maybe if the engine runs with the old coil, you can return the new coil. I’ll keep my fingers crossed for you on that one.

(BAS)

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